Dusty star could conceal alien 'Earth'

Rocky planets make a comeback

US Astronomers have discovered a sun-like star wrapped in a shroud of dust, prompting speculation that the system could harbour a young Earth.

The star, named (poetically as always) BD +20 307, lies around 300 light-years away from us, in the constellation of Aries, but could still shed light on the formation of rocky, Earth-like planets.

The observations, carried out using the Gemini and Keck telescopes in Hawaii, reveal an extremely dusty system. In fact, it is the dustiest environment ever observed so close to a star so similar to our sun - around a million times dustier than our solar system.

In addition, the dust seems to have been produced by collisions of asteroids, or even planet-sized objects at a distance from the star comparable to the Earth's orbit around the sun. The researchers speculate that the collisions must have been fairly recent, and very intense to produce so much debris.

"The amount of warm dust near BD+20 307 is so unprecedented I wouldn't be surprised if it was the result of a massive collision between planet-size objects, for example, a collision like the one which many scientists believe formed Earth's moon," said Benjamin Zuckerman, UCLA professor of physics and astronomy and a co-author on the paper, published in the latest issue of Nature.

Researchers estimate that the star, slightly larger than the sun, is around 300m years old. This means any large planets, like Jupiter, would already have formed, and would influence the dynamics of rocky planet formation. The collisions that produced the dust in this system must the researchers say, have been between objects at least 300km across.

"Whatever massive collision occurred, it managed to totally pulverize a lot of rock," said team member Alycia Weinberger. ®